Electric-lighting apparatus.



Pa'tented Oct. 29, I90l.

W. NEBNST. ELECTRIC LIGHTING APPARATUS.

(Application filed Nov. 7, 1899.)

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fn'ucv'uar mm WM Wmsacs: g $65M No. 685,726. Patented Oct. 29, 190i.

W. NERNST.

ELECTRIC LIGHTING APPARATUS.

(Application fileyi Nov. 7, 1899.) (No .'flude|.) 2 Sheets-Sheet 2.

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'NITED STATES PATENT Fries.

WALTHER NERNST, OF GoTTINGEN, GERMANY, ASSIGNOR TO GEORGE WESTINGHOUSE, OF PITTSBURG, PENNSYLVANIA.

ELECTRIC4LIGHTING APPARATUS.

SPECIFICATION forming part of Letters Patent N 0. 685,7.26, dated October 29, 1901. Original application filed April 23;. 1893, Serial No. 679,081. Divided and. this application filed November 7, 1899. semi No. 736,122. (No model.)

To all whom it may concern 1 Be it known that I, WA'nrHEs N ERNST, a subject of the Emperor of Germany, and a resident of Gottingen, Germany, have invented certa-in new and useful Improvements in Electric-Lighting Apparatus, of which the following is a specification.

Myinvention relates in a general way to the class of devices known as incandescent electric lamps and amethod of lighting; but it difiers fundamentally from the incandescent lamps and methods heretofore used and involves certain peculiar features and characteristics which justify its classification as a distinct and novel species.

I-Ieretofore all practical incandescent electric lamps have comprised a filament of conducting material, usually, if not always, of carbon, contained with an inclosing chamber from which the air is exhausted. The fact that the filaments heretofore employed will oxidize when heated in the open air has necessitated inclosing them in vacuum-chambers.

Various refractory materials comprising certain OXldS, sulfids, silicates, and other salt-like compositions of metals are specially qualified to emit light when heated to a high temperature. It has been proposed to utilize the light-emitting qualities of such materials by maintaining them in a state of incandesc'ence by a gas-flame, as illustrated by the well-known Welsbach bnrnerjjforinstance. When the light-emitting qualities of these refractory materials were to be used in connection with electriclighting at ordinary voltages, it has heretofore been considered necessary to either maintain them in an incandescent state by placing them in proximity to conductors heated by electric currents or to coat them oradd to them or in some waycombine with them some good conducting material, such as a metal or carbon, which should afiord a conducting-path for the current. For example, it. has been proposed to impregnate or coat conductors such, for instance, as platinum, iridium or carbon-with arefractory material-such, for instance, as calcium or. zirconia-and to; use the heat developed in the conducting material for maintaining the refractory material in an incandescent lightemitting condition. Such combinations, however; have been found to be inoperative for any useful purpose. The platinum or carbon or other conducting material either itself melts or disintegrates or causes the r'efrac-' tory material to crack off or disintegrate.

1 have discovered that certain refractory salt=like combinations, particularly oXids usually classed as the rare earths, which are at ordinary temperatures non-conduc tors of electricity, as that term is usually em ployed, will when raised to the high temperature of incandescence become sufficiently good conductors to permit the passage of an electric current under moderate difieren'ces of potential and'maybe maintained sufficiently heated to retain their thus-acquired conduct ing qualities by the passage of the electric current therethrough. These materials when so traversed by electric currents not only emit more light underthe influence of a given amount of electrical energy than the ordinary ent from those 'of the ordinary incandescent electric lamp thatfto term it a filament would be not onlyinappropriate, but to a certain extent misleading. The light is emitted therefrom without combustion or material disintegration even when exposed to the air, and being translucent it emits light from its interiorand from its surface, and I have given the name glower to the light-giving porv tioned oxid of magnesium or magnesia and it I oxid of zirconium or zirconia; also, the oxids of yttrium, cerium, thorium, and the like. These materials when in a dry state and at normal temperatures are practically insulators or non-conductors; but when glowers made from them are heated to a state of incandescence they acquire conducting qualities to such an extent that electricity may be caused to pass through them at ordinary low pressures in sufficient quantities to keep them in the state of incandescence even after the means employed for imparting the original starting-heat is withdrawn. Instead of using these materials individually or alone for forming the glower two or more of them may be mixed or combined in varying proportions with advantageous results. Glowers made from a proper mixture of certain of the materials will pass into the conducting state at a lower initial or starting temperature than will a glower made from one of the materials alone and will maintain under the passage of the electric current a luminous condition without deterioration better and for a longer time than will any single one of such materials. It is not therefore the mere mixture of such materials that I prescribe, but the utilization of such mixtures, on account of their superior properties when brought to and maintained in a luminous condition. Glowers made from these materials even when in their best operating conducting condition have a specific resistance so great with reference to that of carbon that a glower to be used With a given voltage may be much shorter and thicker than the carbon filament of an ordinary incandescent lamp. For instance, a practical glower of, say, one-fiftieth of an inch in diameter and one-half an inch in length may be made which when heated to a low incandescence will become a sufficiently good conductor to be traversed under a one-hundred volt difference of potential by a sufficient current to bring it to and maintain it at a state of high incandescence. A current of, say, four-tenths of an ampere, or thereabout will accomplish this result.' As the material has sufficient strength to enable it to be used in much longer lengths than that above referred to, it is possible to construct lamps adapted to be operated at very much higher voltages than is practicable with lamps using carbon filaments, a feature which may be utilized to obtain economy of transmission. This feature, in connection with the high efficiency of the lamp, renders it possible to secure either a given illumination with a much higher transmission efficiency than at present obtained or a higher illumination with the present transmission efficiency, or both the illuminating and the transmission efficiencies may be materially increased.

There are numerous different proportions in which the different refractory materials adapted to the purposes of my invention may be used, and there is a very Wide range for the selection of the different materials to be mixed together, and therefore I will attempt only, and it will only be necessary, to specify one or two examples. Very excellent results have been obtained from a mixture of approximately seventy per cent. of zirconia and thirty per cent. of yttria, (oxid of yttrium.) Another mixture which I have used with good advantage consists approximately of ten per cent. of zirconia, seventy per cent. ofthoria, and twenty per cent. of ytt'ria. I have also obtained excellent glowers from a mix ture of about seventy per cent. of thoria and thirty per cent. of yttria. Another mixture consists of 0.5 per cent. of cerium, eighty per cent. of thoria, with 19.5 per cent. of yttria. These percentages may be widely varied, and, generally speaking, the oxids of the rare earths are well adapted for mixture in widely-varying proportions.

The process of preparing the glowers from which I have heretofore obtained the best results when two or more of the oxids are to be used together consists in thoroughly pulverizing and mixing the materials together into very intimate relations, then mixing therewith a binder of clear-starch paste, making a plastic mass which should be thoroughly worked. The Water used in making the paste should be clear and preferably distilled to avoid the presence of lime, which is more volatile than the oxids of the rare earths, and therefore undesirable. The plastic mass may then be inserted in a press adapted to force the mixture through a small hole of the requisite diameter, dependent upon the ultimate diameter desired for the glower, and as the material leaves the press it may be hung over a glass rod or laid upon a suitable supporting-surface and allowed to dry. The material acquires sufiicient strength when dried to be conveniently handled, and it is then heated to a very high temperature in any suitable manner-for instance, in an oxyhydrogen flame. It is desirable that as great a specific gravity as possible may be given to the material-=that is to say, the smallest diameter for a given mass of a given length. Care should be taken that every part ofthe glower is brought to a high incandescence. Usually it is advantageous to heat the material gradually, so as to drive oi the moisture, and the binding material slowly, and thus lessen the liability of the surface becoming cracked. For example, it may be passed through a preliminary heat in aporcelain kiln. The eventual heating, however,should be carried to an extremely high temperature. When the material has been thus prepared, a proper length, dependent upon the voltage and the current with which it is to be used, is mounted between two suitable conducting-wires. The ends may advantageously be fastened mechanically in any suitable way-as, for instance, by inserting them into suitable sockets made by forming into spirals the conducting-wires, which may be of platinum or other good conducting materials which melt only at a very high temperature. The j unctions of the glower with the respective wires are then built up by placing thereon, in a liquid or paste-like condition, small quantities ofa cementing material and heating and drying the same in a gas-flame or otherwise. This process is repeated until a firm union is obtained between the respective ends of the glower and the wires. It is advantageous also to make the points of juncture with the wires of larger diameter than the main portion of the glower, for then thepoints of contact with the wire will not during the operation of the lamp be as hot as the-remainder of the glower, and therefore the wires themselves are less liable to burn off. The paste or cement with which it is desirable to build up the ends may be of the same material as that used for forming the glower itself. I have obtained excellent results by pulverizing portions of glowers, which have been previously prepared and heated to high temperatures, and mixing the the immediate vicinity of the glower.

same with water, and, if desired, starch paste may be added. Any suitable means for supporting the conducting-wires and securing electrical connections therewith may be' employed.

For the purpose of obtaining the preliminary or starting heating of the glower various dilferent means may be employed. Usually it is desirable that the heat should be applied only during the starting process and thenwithdrawn, although in some cases it may be desired to continue the extraneous heat while the lamp itself is in operation.

A very convenient starting-heater consists of a coil of platinum wire or other condu'oting material, which may be heated to a high temperature in the open air by the passage of electric currents without being melted. This wire is coiled or otherwisev arranged in such proximity to the glower that when heated by the passage of an electric current it will raise the glower to a sufficiently high temperature to cause it to acquire the necessary conducting capacity to permit sufficient current to flow through it, under the influence of the difference of potential of the circuit upon which it is to be used, to carry it to a state of high incandescence and maintain it there. When the lamp has once been started, the cir-. cuit through the heater maybe interrupted manually or automatically, and, if it is desired, the heater may also be withdrawn from Instead of imparting the starting-heat by the agency of electric currents other extraneous sources of heat may be employed-as, for instance, a gas-flame or the flame of a lamp, or even a match in some instances.

The temperature to which the glower must be brought in order to have sufficient conductivity to allow enough current to flow through it to maintain itself in that conductive condition varies somewhat with different materials and proportions. Some of the mixtures will prod uce a glower which when heated to a conductive temperature will fall in resistance so rapidly under the influence of a constant difference of potential as to permit a current to flow which would be destructive to the. glower. With such glowers means should be employed for counteracting this effect and cause the glower to receive and consume only a predetermined amount of current, and therefore remain at a predetermined safe temperature. A convenient means for accomplishing this result with such glowers consists in introducing in series with the glowers a correctly-proportioned resistance, preferably having a high positive temperature coeflicient, and therefore offering an increasing opposition to the flow of the current with increments of current. Resistances com posed of materials having little or no positive temperature corrections may, however, be used in certain cases. In constant-potential alternating-current circuits reactive coils may be used in lieu of such a resistance as above referred to. The expenditure of energy in such compensating devices when required may be very low, as their effective resistance may be in some cases as low as two per cent, or even less, of, the resistance offered by the glower when in operation if the lamps are used upon circuits having little or no variation in difference of potentialas, for in-- stance, storage-battery circuits. When used 'upon circuits subject to wider variations, it may be desirable that this resistance should In the accompanying drawings, illustrating my invention, Figure 1 is a view, partly in diagram, of a complete lamp. Fig. 2 is a detail thereof. Figs. 3 and 4 illustrate modifications. Fig. 5 illustrates certain circuit connections which may be employed for operating the lamp. Fig. 6 illustrates a modification of the organization ofapparatus. Fig. 7 is an enlarged view of a glower.

Referring to the figures, 0 represents a suitable base for supporting the lamp. It is provided with a circuit-closing device D, by means of which the circuit from anysuitable source G of electric currents may be completed to the binding-posts c c of the lamp.

The light-giving portion or glower A of the lamp is made in accordance with the description hereinbefore given. It is carried by two conductors a a of any suitable character, and these are connected with the terminals 0 c of the lamp. A bridge-piece a may be employed for holding the conductors-a a in their proper relative position. A heating or starting conductor Bis shown in Fig. 1 as carried upon a glass or other transparent support I), and it incases to a greater or less extent the glower A. The circuit through the heater B is completed from the terminal 0 through the wire 2, circuit-closer or switching device 3, of any suitable character, and

IIIO conductor 3 to one terminal of the heater, the other terminal being connected by the con ductors at and 6 to the remaining terminal 0 of the lamp. The terminals 0 c are connected across the circuit L L The glower itself is connected in parallel circuit with the heater by way of conductors 5 and 6 and the Supporting wires a and a When the switches D and sare closed, the current passes through the heater B, raising the glowerA to such a temperature as will render it sufficiently conductive to be traversed by a current from the generator. The circuit through the heater may then be interrupted by the switch 5, or in some cases it may remain in circuit while the lamp is in operation; but in such case the watts expended in the heater or starting-conductor B should be as few as possible consistent with its function of heating the glower. I usually prefer, however, to so arrange the starting-conductor that its circuit shall be interrupted when it has performed its function of heating the glower to its conducting condition, and in that case the watts consumed in the starting-conductor during the short time the circuit is closed through it becomes unimportant. The interruption of the starting-circuit may be either manual or automatic, as shown in Fig. 5, for instance.

The lamp itself may be, if desired, inclosed in a protecting-globe E of any suitable character; but it is not necessary that it should be incased at all, as it will operate in the air. As the light emitted by the glower is very intense, it may be desirable in some cases to use a so-called opaleseent globe or other means to diffuse the light. The globeEmay be held in place in any convenient manner, as by clips 6 e, for instance.

In Figs. 3 and 4 a modification of the invention is illustrated in which a glower is placed at or near the focus of a concave reflector, which at the same time constitutes a support for the heating-conductor B. This support H is here shown as being concave, and it may be of any suitable non-conducting heat-resisiting material-such, for instance, as porcelain. The heating-conductor may be embedded in the material. I have here shown suitable supporting-clipsffor receiving the ends of the supports a a so that the glower may be readily replaced. The support H is shown as carried upon suitable standards 0, extending from a base 0. Conductors for establishing a connection with the heater are connected through suitable binding-posts with the conductors 1 2, leading to the terminals of the heater, and conductors 5 and 6 are shown as leading to the standards 6 b carrying the clips ff.

In Fig. 5 I have shown an organization of circuits for automatically interrupting the circuit connections of the starting-conductor B. This consists of a movable core or armature is and its solenoid or actuating coil K. This coil is placed in circuit with the glower A, and when the current is established through the glower the core is attracted by the solenoid, and the switch 3, which is interposed in the heater-circuit, is automatically opened and will remain open so long as the lamp is in operation. hen the current through the glower is interrupted, the switch will automatically close and be in position for relighting the lamp when desired.

In Fig. 6 I have illustrated a modification in which the glower is movable with reference to the heating-support H and its conductor B. The glower is here shown as being carried bya support K, which is steadied by a guide-rod 1', extending through an opening r. The support K is movable and is carried by the core is of a solenoid K. The solenoid is connected in series with the glower A, so that when current passes through the glower the action of the solenoid is to draw the core within itself, thus moving the glower out from the inclosing heater-support H. A spring t may be employed for sustaining the core k and the connected parts and rendering the parts movable under the influence of a relatively small amount of current. I have also shown the heater as being supplied from a separate source G of electricity instead of being in a branch circuit from the source G. Such a separate generator may of course be used in other instances. An automatic circuit-interrupting device may be placed in the circuit of the heater in this case as well as in the others, if desired. The interruption of thecircuit through the glower automatically restores the parts to the position shown. The initial starting-heat may be given to the glower in other ways than by heat supplied by an electric current. Any source of heat which may be conveniently supplied in sufficient quantities to raise it to its conducting temperature may be used. By these and other similarmethods suificient initial starting-heat may be given to the glower in a few seconds, and the flow of current through the glower itself then generates heat,and thus quickly brings it to a state of high incandescence. The Joule heat thus generated in the glower will serve to maintain this high incandescence and light-emitting condition.

In cases where there is liable to be an undue increase in the amount of current flowing through the glower when placed upon a constant-potential circuit means (such as indicated at B) may be employed for preventing such an increase. The device R is shown as being placed in series with the lamp itself and, as hereinbefore explained, may consist of a properly-proportioned resistance or im pedance coil, according to the character of the circuit. For continuous-current circuits the resistance may be made of suitable metal of high specific resistance such, for instance, as platinum or iron--and properly proportioned to prevent an increase of current through the lamp except under the influence of an increase of potential. In the case of ICC IIC

lamps used on an alternating-current circuit properly-proportioned reactive or impedance coils may be used.

Although I have described the invention more particularly with reference to open-air use, I desire it to be understood that it may also be used in vacuum-chambers, if desired.

In certain other applications filed by me for instance, Serial No. 718,624, filed May 29, 1899; Serial No. 55,221, filed April 10, 1901; Serial No. 55,222, filed April 10, 1901, and Serial No. 679,081, filed April 28, 1898, of which this application is a division-claims are made to certain features and methods of operating electric lights described herein.

I claim as my invention- 1. In an electric lamp,the combination with an incandescing body that is a non-conductor when cold and a conductor when heated to a high temperature, of a resistanceconductor, and a sleeve or mantle of refractory non-conductive material supporting the same andplaced in the vicinity of or surrounding the said incandescent body, means for heating said resistance-conductor by electric currents and means for moving said incandescing body from Within said sleeve or mantle.

2. In electric lamps, the combination with an incandescent body made of a material that is a non-conductor when cold and becomes a conductor when heated to a high temperature, of a resistance-conductor, a supporting sleeve or mantle of heat-proof, non-conductive material surrounding the said incandescent body, and means for automatically moving the latter from within said sleeve as soon as a current traverses it, substantially as and for the purpose described.

3. In an electric glowlamp, a movable glower, a heater separate fromthe glower, circuit-controlling mechanism in the circuits of said heater and glower, and means for opcrating said mechanism.

4:. In anclectric glow-lamp, a movable glower, a heater separate therefrom, circuitclosing mechanism for closing circuit simultaneously through said heater and glower, and means for operating said mechanism.

5. In an electric glow-lamp, a movable glower, a heater separate therefrom, circuitbreaking mechanism for breaking circuit through said heater and glower, and means for operating said mechanism.

6. In an electric lamp, a movable glower, an electric heater separate therefrom, mechanism for cutting the heater out of circuit, and automatic means for operating said mechanism when current traverses said glower.

7. In an electriclamp, the combination of a glower, a concave reflector, and a heatingconductor for raising the glower to a conducting temperature, carried by the reflector.

8. In electrical incandescentlamps,thc coinbination with an incandescent body made of a material that is a non-conductor when cold and becomes a conductor when heated to a high temperature, of a wire resistance com= bined with a mantle of heat-proof non-conductive material, said mantle being shaped like a concave mirror and being placed in the' vicinity of said incandescent body in such a position that the latter is in its focus, substantially as and for the purpose described. 9. In a heater for an electric lamp of the type herein specified, a body of insulating material having a concave arch-shaped face, and a heating-conductor disposed on said face.

10. In' an electric lamp of the type herein specified, a heater in the form of an arch, and a glower in the form of a rod or bar, disposed parallel to the arch.

11. In an electric lamp of the type herein specified, a heater-support of insulating refractory material in the form of an arch, a heater in the form of a wire or filament disposed on the inner surface thereof, and a glower in the form of a rod or bar disposed parallel to the arch.

12. In an electric lamp,a glower,a fixed electric heater in proximity thereto, and means for automatically breaking circuit through said heater.

13. In an electric lamp,a glower,a fixed electric heater in proximity thereto, and means controlled by the current in said glower for automatically cutting said heater out of cir- 16. In an electric lamp, a heater, a glower,"

and means for detachably securing said glower in definite position with respect to the heater.

17. In electric lamps, the combination with an incandescent body made of a material that is a non-conductor when cold and becomes a conductor when heated to a high temperature, of a resistance-conductor combined with a concave mantle of heat-proof non-conducting material, placed in the vicinity of said incandescent body in such a position that the latter is near its focus.

18. In an electric lamp, the combination of a glower, supports connected with the respective terminals, an insulating cross-bar connecting the supports, and supporting-clips for detachably holding said supports.

Signed by me at Basle this 18th day of October, 1899.

WALTHER NERNST. Witnesses:

JOHN G. PLA'INER, GEORGE Gmroao. 

